Quality-of-service and call admission control

ABSTRACT

An apparatus and methods are disclosed for enabling quality-of-service and call admission control for wireless telecommunications terminals without first submitting a traffic specification. The illustrative embodiment of the present invention is particularly advantageous for IEEE 802.11e networks because the 802.11e standard, which in its currently-drafted form contains provisions for terminals to submit traffic specifications, might not require 802.11e terminals to submit traffic specifications in the finalized 802.11e standard. Proper call admission control and, consequently, quality-of-service for wireless applications therefore might not be universally available to future 802.11e-compliant terminals unless one or more embodiments of the present invention are deployed.

REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication Ser. No. 60/478,821 filed 17 Jun. 2003, entitled “Method ForCoupling Call Admission Control And Shared Bandwidth Management,”, whichis also incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to telecommunications in general, and,more particularly, to quality-of-service (QoS) and admission control.

BACKGROUND OF THE INVENTION

FIG. 1 depicts a schematic diagram of telecommunications system 100 inthe prior art. Telecommunications system 100 comprisestelecommunications terminals 101-1 and 101-2, network 110, and server120, interconnected as shown. Network 110 is a communications networksuch as the Internet, the Public Switched Telephone Network (PSTN),etc., as is well-known in the art. Telecommunications terminals 101-1and 101-2 are devices such as personal computers, telephones, etc. thatcommunicate with other telecommunications terminals via network 110.Each telecommunications terminal has an associated contact identifier(e.g., telephone number, email address, Internet Protocol address, etc.)that uniquely identifies that terminal in the address space oftelecommunications system 100. Server 120 (e.g., a Session InitiationProtocol [SIP] server, an SIP proxy server, etc.) maintains a list thatmaps user identifiers (e.g., user names, social security numbers, etc.)to contact identifiers.

Server 120 enables the users of telecommunications terminals tocommunicate as illustrated by the following example: A first user, theuser of telecommunications terminal 101-1, enters a command into theterminal to place a call (e.g. voice call, email, text chat, video,etc.) to a second user. Telecommunications terminal 101-1 sends via anappropriate protocol (e.g., the Session Initiation Protocol [SIP], etc.)a message (e.g., an SIP INVITE message, etc.) server 120 that requeststhe contact identifier of the telecommunications terminal associatedwith the second user (i.e., the terminal that the second user iscurrently using). Server 120 then sends a response (e.g., an SIPacknowledgement [ACK], etc.) to telecommunications terminal 101-1 thatindicates whether the second user can be reached, and if so, theassociated contact identifier. Upon receiving the associated contactidentifier, telecommunications terminal 101-1 sends one or more messagesdirectly to telecommunications terminal 101-2 via network 110, andtelecommunications terminal 101-2, which obtains the contact identifierof telecommunications terminal 101-1 via the received message(s), canrespond directly to telecommunications terminal 101-2 via network 110.

FIG. 2 depicts a schematic diagram of wireless local-area network 200 inthe prior art, which comprises access point 201 and wireless terminals202-1 through 202-N, wherein N is a positive integer, interconnected asshown. Each wireless terminal 202-i, wherein i is member of the set ofpositive integers {1, . . . N}, is a device (e.g., a notebook computer,personal digital assistant [PDA], tablet PC, etc.) that communicateswirelessly with other terminals in network 200 via access point 201.

Access point 201 and wireless terminals 202-1 through 202-N transmitmessages over a shared-communications channel such that if two or morewireless terminals (or an access point and a wireless terminal) transmitmessages simultaneously, then one or more of the messages can becomecorrupted (which results in a collision and the destruction of bothmessages). As a consequence, local-area networks typically employprotocols for ensuring that a wireless terminal or access point can gainexclusive access to the shared-communications channel for an interval oftime in order to transmit messages without collisions.

Such protocols can be classified into two types: contention-basedprotocols, and contention-free protocols. In a contention-basedprotocol, wireless terminals 202-1 through 202-N and access point 201compete to gain exclusive access to the shared-communications channel.

In a contention-free protocol, in contrast, a coordinator (e.g., accesspoint 201, etc.) grants access to the shared-communications channel toone station at a time. One technique in which a coordinator can grantaccess to the shared-communications channel is polling. In protocolsthat employ polling, stations submit a polling request to thecoordinator, and the coordinator grants stations exclusive access to theshared-communications channel sequentially in accordance with a pollingschedule.

The Institute of Electrical and Electronics Engineers (IEEE) 802.11especification is an emerging set of protocols that providesquality-of-service (QoS) for wireless local-area networks, in additionto contention-based and contention-free shared-communications channelaccess. Quality-of-service is an important consideration for wirelesslocal-area networks given the serialization of communications imposed bythe shared-communications channel, as well as the growing bandwidthrequirements of various applications. An IEEE 802.11e-compliant wirelessterminal can transmit to the wireless access point a request to add atraffic stream (ADDTS), accompanied with the following information:

-   -   (i) a traffic specification (TSPEC) that specifies one or more        parameters of future traffic that will be generated by the        terminal (e.g., a temporal period for periodic traffic streams,        a minimum service interval, a maximum service interval, etc.);        and    -   (ii) a traffic class that indicates the priority of future        traffic.

The access point will either accept or decline the request, depending onthe available bandwidth. If the request is declined the station may nottransmit with the privileges of the traffic class indicated in theTSPEC. The ability of an access point to decline an ADDTS requestenables bandwidth management, also known as “over-the-air admissioncontrol.” request enables bandwidth management, also known as“over-the-air admission control”.

SUMMARY OF THE INVENTION

The present invention enables quality-of-service and over-the air calladmission control for wireless terminals that engage in communicationswithout first submitting a traffic specification (TSPEC). Theillustrative embodiment of the present invention is particularlyadvantageous for IEEE 802.11e networks because the 802.11e standard,which in its currently-drafted form contains provisions for terminals tosubmit traffic specifications, might not require 802.11e terminals tosubmit traffic specifications in the finalized 802.11e standard. Propercall admission control and, consequently, quality-of-service forwireless applications therefore might not be universally available tofuture 802.11e-compliant terminals unless one or more embodiments of thepresent invention are deployed.

The illustrative embodiment employs a gateway that connects to thewireless access points of one or more local-area networks (LANs) andsits between the LANs and a network (e.g., the Internet, the PublicSwitched Telephone Network (PSTN), etc.) that connects to a server(e.g., a Session Initiation Protocol [SIP] server, an SIP proxy server,etc.). In the illustrative embodiment, a first user's wireless terminalplaces a call to a second user by sending to its wireless access point amessage that comprises: (i) a traffic stream description (e.g., an SIPReal-Time Protocol [RTP] payload type, etc.) that specifies the natureof a call (e.g., a voice telephone call, a video conference, atext-based instant message [IM], etc.), and (ii) a request for thecontact identifier of the second user's telecommunications terminal. Themessage might also optionally include one or both of (iii) a trafficcategory, and (iv) a traffic specification. The wireless access pointsends the message to the gateway for forwarding to the server. Thegateway, before forwarding the message to the server, stores the trafficstream description (and if present, the traffic category and trafficspecification) in a record associated with the call. In someembodiments, the gateway might include in the record a measure ofcommunication resource usage of the shared-communications channel (e.g.,channel capacity utilization, etc.) or might append this measure to themessage before forwarding.

The server 120 then sends a response (e.g., an SIP acknowledgement[ACK], etc.), to the first user's telecommunications terminal via thenetwork, gateway, and wireless access point that indicates whether thesecond user can be reached, and if so, the associated contactidentifier. The gateway, upon receiving the response, intercepts theresponse instead of forwarding the response to the appropriate wirelessaccess point. When the response contains a positive acknowledgement, thegateway consults the appropriate record and checks whether a trafficspecification was provided for the call. If no traffic specification wasprovided, the gateway determines, based on the traffic streamdescription and measure of communication resource usage, whether theamount of communication resource (e.g., bandwidth, channel idleness,etc.) currently available is sufficient to support the call (i.e.,whether the call should be admitted). The gateway then sends a messageto the server that indicates whether the call is admitted, and theserver proceeds accordingly.

A similar process occurs when a call is directed to a wireless terminal.

Although the illustrative embodiment of the present invention isdisclosed in the context of IEEE 802.11e local-area networks, it will beclear to those skilled in the art how to make and use embodiments of thepresent invention for other kinds of networks and network protocols. Inaddition, the term “call,” while normally used only in the context oftelephone voice calls, will be used to encompass all manners ofcommunication (e.g. email, text chat, video, etc.), and it will be clearto those skilled in the art how to make and use embodiments of thepresent invention for such alternative means of communication.

The illustrative embodiment comprises: (a) a receiver for receiving afirst message from a server, wherein the first message is based on asecond message that (i) is sent from a first telecommunications terminalto the server, and (ii) specifies a traffic stream description for acall initiated by a second telecommunications terminal and directed tothe first telecommunications terminal, and wherein the first messagecomprises an estimated communication resource requirement for the callthat is based on the traffic stream description for the call; (b) aprocessor for determining whether to admit the call based on (i) theestimated communication resource requirement for the call, and (ii) ameasure of communication resource usage of a shared-communicationschannel associated with the first telecommunications terminal; and (c) atransmitter for transmitting a third message to the server thatindicates whether the call is admitted.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a schematic diagram of an exemplary telecommunicationssystem in the prior art.

FIG. 2 depicts a schematic diagram of an exemplary wireless local-areanetwork in the prior art.

FIG. 3 depicts a schematic diagram of a telecommunications system thatinvolves at least one wireless terminal, in accordance with theillustrative embodiment of the present invention.

FIG. 4 depicts a schematic diagram of wireless local-area network 301-i,as shown in FIG. 3, in accordance with the illustrative embodiment ofthe present invention.

FIG. 5 depicts a block diagram of the salient components of wirelessaccess point 401, as shown in FIG. 4, in accordance with theillustrative embodiment of the present invention.

FIG. 6 depicts a block diagram of the salient components of gateway 306,as shown in FIG. 3, in accordance with the illustrative embodiment ofthe present invention.

FIG. 7 depicts a block diagram of the salient components of server 320,as shown in FIG. 3, in accordance with the illustrative embodiment ofthe present invention.

FIG. 8 depicts the message flows associated with a wireless terminalplacing a call, in accordance with the illustrative embodiment of thepresent invention.

FIG. 9 depicts the message flows associated with an admitted call placedby a wireless terminal, in accordance with the illustrative embodimentof the present invention.

FIG. 10 depicts the message flows associated with a rejected call placedby a wireless terminal, in accordance with the illustrative embodimentof the present invention.

FIG. 11 depicts the message flows associated with a wireless terminalreceiving a call, in accordance with the illustrative embodiment of thepresent invention.

FIG. 12 depicts the message flows associated with an admitted call to awireless terminal, in accordance with the illustrative embodiment of thepresent invention.

FIG. 13 depicts the message flows associated with a rejected call to awireless terminal, in accordance with the illustrative embodiment of thepresent invention.

DETAILED DESCRIPTION

For the purposes of the specification and claims, the term “trafficstream description” is defined as a datum that specifies (i) the natureof a traffic stream associated with a call (e.g., a voice trafficstream, a video stream, a text-based instant message [IM] trafficstream, etc.), and, optionally, (ii) one or more parameters associatedwith the traffic stream (e.g., periodicity, bandwidth requirements,latency tolerance, etc.)

For the purposes of the specification and claims, the term “call” isdefined as communication between two or more terminals (e.g. a voicetelephone call, an email, a text-based instant message [IM] session, avideo conference, etc.).

For the purposes of the specification and claims, the term“communication resource usage” is defined as a datum that characterizesusage of a communication resource (e.g., bandwidth, channel idleness,etc.) associated with a communication medium.

FIG. 3 depicts a schematic diagram of telecommunications system 300 thatinvolves at least one wireless terminal, in accordance with theillustrative embodiment of the present invention. Telecommunicationssystem 300 comprises one or more wireless local-area networks 301-ithrough 301-K, where K is a positive integer; gateway 306; server 320;and network 110, as described above and with respect to FIG. 1;interconnected as shown.

Wireless local-area networks 301-i through 301-K, are similar towireless local-area network 200 of FIG. 2, with the exception ofdifferent wireless terminals and wireless access points employed in lieuof terminals 202 and access point 201, respectively. Wireless local-areanetworks 301-i through 301-K are described in detail below and withrespect to FIG. 4.

Gateway 306 connects wireless local-area networks 301-i through 301-K tonetwork 110 in well-known fashion. In addition, gateway 306 performslogic, receives messages from wireless local-area networks 301-i through301-K and from network 110, and transmits messages to wirelesslocal-area networks 301-i through 301-K and to network 110, as describedbelow and with respect to FIG. 6 and FIGS. 8 through 13.

Server 320 provides the functionality of server 110 in the prior art,and in addition, transmits special call-setup TSPEC (CS-TSPEC) messagesas described below and with respect to FIGS. 7 through 13.

FIG. 4 depicts a schematic diagram of wireless local-area network 301-i,as shown in FIG. 3, in accordance with the illustrative embodiment ofthe present invention. Wireless local-area network 301-i compriseswireless access point 401, and wireless terminals 402-1 through 402-N,interconnected as shown.

Wireless access point 401 provides the functionality of access point 201in the prior art, and in addition, appends information to call-setupmessages sent from wireless terminals 202, as described below and withrespect to FIGS. 8 through 13.

Wireless terminals 402-1 through 402-N provide the functionality ofwireless terminals 302 in the prior art, and in addition, providedadditional quality-of-service services in accordance with a particularprotocol (e.g., IEEE 802.11e, etc.). In the illustrative embodiment,wireless terminals 402-1 through 402-N are IEEE 802.11e terminals, whereeach terminal 402-i might or might not provide a traffic specification(TSPEC) for call requests.

FIG. 5 depicts a block diagram of the salient components of wirelessaccess point 401, in accordance with the illustrative embodiment of thepresent invention. Wireless access point 401 comprises receiver 501,processor 502, memory 503, and transmitter 504, interconnected as shown.

Receiver 501 is a circuit that is capable of receiving messages fromwireless terminals 402-1 through 402-N and from gateway 306, inaccordance with FIGS. 8 through 13 below, and of forwarding the messagesto processor 502. It will be clear to those skilled in the art how tomake and use receiver 501.

Processor 502 is a general-purpose processor that is capable ofexecuting instructions stored in memory 503, of reading data from andwriting data into memory 503, and of executing the tasks described belowand with respect to FIGS. 8 through 13. In some alternative embodimentsof the present invention, processor 502 is a special-purpose processor(e.g., a network processor, etc.). In either case, it will be clear tothose skilled in the art, after reading this disclosure, how to make anduse processor 502.

Memory 503 is capable of storing programs and data used by processor502, as is well-known in the art, and might be any combination ofrandom-access memory (RAM), flash memory, disk drive, etc. It will beclear to those skilled in the art, after reading this specification, howto make and use memory 503.

Transmitter 504 is a circuit that is capable of receiving messages fromprocessor 502, in well-known fashion, and of transmitting the messagesto wireless terminals 402-1 through 402-N and to gateway 306 inaccordance with FIGS. 8 through 13 below. It will be clear to thoseskilled in the art how to make and use transmitter 504.

FIG. 6 depicts a block diagram of the salient components of gateway 306in accordance with the illustrative embodiment of the present invention.Gateway 306 comprises receiver 601, processor 602, memory 603, andtransmitter 604, interconnected as shown.

Receiver 601 is a circuit that is capable of receiving messages fromwireless local area networks 301 and from network 110 in accordance withFIGS. 8 through 13 below, and of forwarding these messages to processor602. It will be clear to those skilled in the art how to make and usereceiver 601.

Processor 602 is a general-purpose processor that is capable ofexecuting instructions stored in memory 603, of reading data from andwriting data into memory 603, and of executing the tasks described belowand with respect to FIGS. 8 through 13. In some alternative embodimentsof the present invention, processor 602 is a special-purpose processor(e.g., a network processor, etc.). In either case, it will be clear tothose skilled in the art, after reading this disclosure, how to make anduse processor 602.

Memory 603 is capable of storing programs and data used by processor602, as is well-known in the art, and might be any combination ofrandom-access memory (RAM), flash memory, disk drive, etc. It will beclear to those skilled in the art, after reading this specification, howto make and use memory 603.

Transmitter 604 is a circuit that is capable of receiving messages fromprocessor 602, in well-known fashion, and of transmitting messages tolocal-area networks 200-i through 200-K and to network 110 in accordancewith FIGS. 8 through 13 below. It will be clear to those skilled in theart how to make and use transmitter 604.

FIG. 7 depicts a block diagram of the salient components of server 320,in accordance with the illustrative embodiment of the present invention.Server 320 comprises receiver 701, processor 702, memory 703, andtransmitter 704, interconnected as shown.

Receiver 701 is a circuit that is capable of receiving messages fromnetwork 110 in accordance with FIGS. 8 through 13 below, and offorwarding these messages to processor 702. It will be clear to thoseskilled in the art how to make and use receiver 701.

Processor 702 is a general-purpose processor that is capable ofexecuting instructions stored in memory 703, of reading data from andwriting data into memory 703, and of executing the tasks described belowand with respect to FIGS. 8 through 13. In some alternative embodimentsof the present invention, processor 702 is a special-purpose processor(e.g., a network processor, etc.). In either case, it will be clear tothose skilled in the art, after reading this disclosure, how to make anduse processor 702.

Memory 703 is capable of storing programs and data used by processor702, as is well-known in the art, and might be any combination ofrandom-access memory (RAM), flash memory, disk drive, etc. It will beclear to those skilled in the art, after reading this specification, howto make and use memory 703.

Transmitter 704 is a circuit that is capable of receiving messages fromprocessor 702, in well-known fashion, and of transmitting messages tonetwork 110 in accordance with FIGS. 8 through 13 below. It will beclear to those skilled in the art how to make and use transmitter 704.

FIG. 8 depicts the message flows associated with the user of wirelessterminal 402-i placing a call, in accordance with the illustrativeembodiment of the present invention.

At time t₀, wireless terminal 402-i, the terminal of the user placing acall, sends a message via wireless access point 401 and gateway 306 toserver 320 (e.g., an SIP INVITE message, etc.). The message comprises:(i) a traffic stream description (e.g., an SIP Real-Time Protocol [RTP]payload type, etc.) that specifies the nature of a call (e.g., a voicetelephone call, a video conference, a text-based instant message [IM],etc.); and (ii) the user identifier of the person to be called. Themessage might also optionally include one or both of: (iii) a trafficcategory, and (iv) a traffic specification (TSPEC). Before transmittingthe message to server 320, gateway 306 stores the traffic streamdescription (and if present, the traffic category and trafficspecification) in a newly-created record associated with this call.

In some other embodiments of the present invention, wireless accesspoint 401 might also append to the message (v) a measure ofcommunication resource usage of the shared-communications channel (e.g.,channel capacity utilization, etc.). In such embodiments, gateway 306,before transmitting the message to server 320, might also store themeasure of communication resource usage in the newly-created record.

At time t₁, server 320 determines which terminal is currently associatedwith the user identifier of the called user (i.e., the “destinationterminal”), and sends a message (e.g., an SIP OPTIONS message, etc.) tothe destination terminal to determine the capabilities of thedestination terminal (e.g., whether the destination terminal supportscertain types of media, etc.).

At time t₂, server 320 sends a response to wireless terminal 402-iindicating that the server is attempting to set up the call, inwell-known fashion.

At time t₃, the destination terminal sends a response to server 320(e.g., an SIP OK message, etc.) in well-known fashion.

At time t₄, server 320 sends a message addressed to wireless terminal402-i called a call-setup TSPEC (CS-TSPEC) request. In the illustrativeembodiment, the CS-TSPEC is not a standard SIP message or an extension,as gateway 306 would not be able to interpret an SIP message addressedto wireless terminal 402-i that is subject to security encapsulation. Inthe illustrative embodiment, the CS-TSPEC message is sent to a specialreserved User Datagram Protocol (UDP) port that gateway 306 monitors, asis well-understood in the art. In some other embodiments, a TransmissionControl Protocol (TCP) socket might be used instead of UDP; however,this might result in decreased efficiency. Like the SIP ResourceReservation Protocol (RSVP), the CS-TSPEC mechanism provides out-of-bandsignaling for bandwidth reservation.

Gateway 306 intercepts the CS-TSPEC request and checks if wirelessterminal 402-i, the calling terminal, included a traffic specification(TSPEC) in the message sent at time t₀. If not, gateway 306 determines,based on the traffic stream description and measure of communicationresource usage stored at gateway 306, whether the amount ofcommunication resource (e.g., bandwidth, channel idleness, etc.)currently available is sufficient to support the call (i.e., whether thecall should be admitted).

At time t₅, gateway 306 sends a message to server 320 that indicateswhether the call is admitted, in well-known fashion. In the illustrativeembodiment, the message is sent to a special reserved UDP port at server320, where it is awaited by a collocated daemon, synchronized with thepending invitation message, described below and with respect to FIG. 9.

If the call was admitted, the message flows of the illustrativeembodiment proceed as described below and with respect to FIG. 9;otherwise, the message flows of the illustrative embodiment proceed asdescribed below and with respect to FIG. 10.

FIG. 9 depicts the message flows associated with an admitted call placedby a wireless terminal, in accordance with the illustrative embodimentof the present invention.

At time t₆, server 320 sends a message to the destination terminal thatinvites the user of the destination terminal to accept the call (e.g.,an SIP INVITE message, etc.), in well-known fashion.

At time t₇, the destination terminal sends a response to server 320indicating that the call is accepted (e.g., an SIP OK message, etc.), inwell-known fashion.

At time t₈, server 320 sends a message to calling terminal 202-iindicating that the call is admitted (e.g., an SIP OK message, etc.), inwell-known fashion.

At time t₉, calling terminal 202-i sends an acknowledgement to server320, in well-known fashion.

At time t₁₀, server 320 sends an acknowledgement to the destinationterminal, in well-known fashion. When the destination terminal receivesthe acknowledgement, calling terminal 202-i and the destination terminalcan communicate as in the prior art.

FIG. 10 depicts the message flows associated with a rejected call placedby a wireless terminal, in accordance with the illustrative embodimentof the present invention.

At time t₆, server 320 sends a message to calling terminal 202-i thatindicates that the call was rejected (e.g., an SIP “488 NOT ACCEPTABLE”message, etc.), in well-known fashion.

At time t₇, calling terminal 202-i sends an acknowledgement to server320, in well-known fashion.

FIG. 11 depicts the message flows associated with a wireless terminalreceiving a call, in accordance with the illustrative embodiment of thepresent invention.

At time t₀, the terminal of the user placing a call, sends a message toserver 320 (e.g., an SIP INVITE message, etc.). The message comprises:(i) a traffic stream description (e.g., an SIP Real-Time Protocol [RTP]payload type, etc.) that specifies the nature of a call (e.g., a voicetelephone call, a video conference, a text-based instant message [IM],etc.); and (ii) the user identifier of the person to be called. If thecalling terminal is a wireless terminal that is compliant with aquality-of-service protocol (e.g., IEEE 802.11e, etc.), the messagemight also optionally include one or both of: (iii) a traffic category,and (iv) a traffic specification (TSPEC).

At time t₁, server 320 determines which wireless terminal 402-i iscurrently associated with the user identifier of the called user, andsends a message to the calling terminal that indicates that the serveris attempting to set up the call, in well-known fashion.

At time t₂, server 320 sends a message to wireless terminal 402-i (e.g.,an SIP OPTIONS message, etc.) that indicates an incoming call, andcomprises items (i) and (ii) above (and potentially one or both of items(iii) and (iv)) in well-known fashion.

At time t₃, wireless terminal 402-i sends, via wireless access point 401and gateway 306, a response to server 320 (e.g., an SIP OK message,etc.) in well-known fashion. Gateway 306, before transmitting themessage to server 320, stores the traffic stream description (and ifpresent, the traffic category and traffic specification) in anewly-created record associated with this call.

In some other embodiments, wireless access point 401 might also appendto this message (v) a measure of communication resource usage of theshared-communications channel (e.g., channel capacity utilization,etc.). In such embodiments, gateway 306, before transmitting the messageto server 320, might also store the measure of communication resourceusage in the newly-created record.

At time t₄, server 320 sends a special message directed to wirelessterminal 402-i that requests a call-setup TSPEC (CS-TSPEC). In theillustrative embodiment, the CS-TSPEC message is sent to a specialreserved User Datagram Protocol (UDP) port that gateway 306 monitors, asis well-understood in the art.

Gateway 306 intercepts the CS-TSPEC request and checks if there is atraffic specification (TSPEC) for the call. If not, gateway 306determines, based on the traffic stream description and measure ofcommunication resource usage stored at gateway 306, whether the amountof communication resource (e.g., bandwidth, channel idleness, etc.)currently available is sufficient to support the call (i.e., whether thecall should be admitted).

At time t₅, gateway 306 sends a message to server 320 that indicateswhether the call is admitted, in well-known fashion. In the illustrativeembodiment, the message is sent to a special reserved UDP port at server320, where it is awaited by a collocated daemon, synchronized with thepending invitation message, described below and with respect to FIG. 12.

If the call was admitted, the message flows of the illustrativeembodiment proceed as described below and with respect to FIG. 12;otherwise, the message flows of the illustrative embodiment proceed asdescribed below and with respect to FIG. 13.

FIG. 12 depicts the message flows associated with an admitted call to awireless terminal, in accordance with the illustrative embodiment of thepresent invention.

At time t₆, server 320 sends a message to wireless terminal 402-i thatinvites the user of the terminal to accept the call (e.g., an SIP INVITEmessage, etc.), in well-known fashion.

At time t₇, wireless terminal 402-i sends a response to server 320indicating that the call is accepted (e.g., an SIP OK message, etc.), inwell-known fashion.

At time t₈, server 320 sends a message to the calling terminalindicating that the call is admitted (e.g., an SIP OK message, etc.), inwell-known fashion.

At time t₉, the calling terminal sends an acknowledgement to server 320,in well-known fashion.

At time t₁₀, server 320 sends an acknowledgement to wireless terminal402-i, in well-known fashion. When wireless terminal 402-i receives theacknowledgement, the calling terminal and wireless terminal 402-i cancommunicate as in the prior art.

FIG. 13 depicts the message flows associated with a rejected call to awireless terminal, in accordance with the illustrative embodiment of thepresent invention.

At time t₆, server 320 sends a message to the calling terminal thatindicates that the call was rejected (e.g., an SIP “488 NOT ACCEPTABLE”message, etc.), in well-known fashion.

At time t₇, the calling terminal sends an acknowledgement to server 320,in well-known fashion.

As will be well-understood by those skilled in the art, when both thecalling terminal and the called terminal are wireless terminals, themessage flows associated with the call will be a composite of themessage flows of FIGS. 8 through 10 and FIGS. 11 through 13.

It is to be understood that the above-described embodiments are merelyillustrative of the present invention and that many variations of theabove-described embodiments can be devised by those skilled in the artwithout departing from the scope of the invention. For example, in thisSpecification, numerous specific details are provided in order toprovide a thorough description and understanding of the illustrativeembodiments of the present invention. Those skilled in the art willrecognize, however, that the invention can be practiced without one ormore of those details, or with other methods, materials, components,etc.

Furthermore, in some instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringaspects of the illustrative embodiments. It is understood that thevarious embodiments shown in the Figures are illustrative, and are notnecessarily drawn to scale. Reference throughout the specification to“one embodiment” or “an embodiment” or “some embodiments” means that aparticular feature, structure, material, or characteristic described inconnection with the embodiment(s) is included in at least one embodimentof the present invention, but not necessarily all embodiments.Consequently, the appearances of the phrase “in one embodiment,” “in anembodiment,” or “in some embodiments” in various places throughout theSpecification are not necessarily all referring to the same embodiment.Furthermore, the particular features, structures, materials, orcharacteristics can be combined in any suitable manner in one or moreembodiments. It is therefore intended that such variations be includedwithin the scope of the following claims and their equivalents.

1. An apparatus comprising: (a) a receiver for receiving a first messagefrom a server, wherein said first message is based on a second messagethat (i) is sent from a first telecommunications terminal to saidserver, and (ii) specifies a traffic stream description for a callinitiated by a second telecommunications terminal and directed to saidfirst telecommunications terminal, and wherein said first messagecomprises an estimated communication resource requirement for said callthat is based on said traffic stream description for said call, whereinsaid first message is directed to said first telecommunicationsterminal, and wherein said receiver intercepts said first message, suchthat said first message is not received at said first telecommunicationsterminal regardless of whether the call is admitted or not admitted,wherein said receiver is also for receiving said measure ofcommunications resource usage of said shared-communications channel froma wireless access point that is associated with saidshared-communications channel, and wherein said processor is also forestimating said measure of communications resource usage of saidshared-communications channel; (b) a processor for determining whetherto admit said call based on (i) said estimated communication resourcerequirement for said call, and (ii) a measure of communication resourceusage of a shared-communications channel associated with said firsttelecommunications terminal; wherein said receiver determines whethersaid first message contains a positive acknowledgment and when saidfirst message does contain a positive acknowledgment then said receiverdetermines whether a traffic specification was provided for said messageand when a traffic specification was not provided then said receiverdetermines, based on the traffic stream description and measure ofcommunication resources usage, whether the amount of communicationresource currently available is sufficient to support the call: and (c)a transmitter for transmitting a third message to said server thatindicates whether said call is admitted.
 2. The apparatus of claim 1wherein said server is for establishing communications betweentelecommunications terminals.
 3. The apparatus of claim 2 wherein saidserver is one of a Session Initiation Protocol server and a SessionInitiation Protocol proxy server.
 4. The apparatus of claim 1 whereinsaid call comprises packets transmitted periodically from said secondtelecommunications terminal to said first telecommunications terminal.5. The apparatus of claim 1 wherein said call comprises packetstransmitted periodically from said first telecommunications terminal tosaid second telecommunications terminal.
 6. The apparatus of claim 4wherein said call also comprises packets transmitted periodically fromsaid second telecommunications terminal to said first telecommunicationsterminal.
 7. The apparatus of claim 1 wherein said processor'sestimating said measure of communications resource usage of saidshared-communications channel is based on at least one message receivedfrom a wireless access point that is associated with saidshared-communications channel.
 8. The apparatus of claim 1 wherein saidfirst message comprises a SIP acknowledgement message and wherein saidsecond message comprises a SIP invite message.
 9. An apparatuscomprising: (a) a receiver for receiving a first message from a server,wherein said first message is based on a second message that (i) is sentfrom a first telecommunications terminal to said server, and (ii)specifies a traffic stream description for a call initiated by saidfirst telecommunications terminal and directed to a secondtelecommunications terminal, and wherein said first message comprises anestimated communication resource requirement for said call that is basedon said traffic stream description for said call, wherein said firstmessage is directed to said first telecommunications terminal, andwherein said receiver intercepts said first message, such that saidfirst message is not received at said first telecommunications terminalregardless of whether the call is admitted or not admitted, wherein saidreceiver is also for receiving said measure of communications resourceusage of said shared-communications channel from a wireless access pointthat is associated with said shared-communications channel, and whereinsaid processor is also for estimating said measure of communicationsresource usage of said shared-communications channel; (b) a processorfor determining whether to admit said call based on (i) said estimatedcommunication resource requirement for said call, and (ii) a measure ofcommunication resource usage of a shared-communications channelassociated with said first telecommunications terminal; wherein saidreceiver determines whether said first message contains a positiveacknowledgment and when said first message does contain a positiveacknowledgment then said receiver determines whether a trafficspecification was provided for said message and when a trafficspecification was not provided then said receiver determines, based onthe traffic stream description and measure of communication resourcesusage, whether the amount of communication resource currently availableis sufficient to support the call; and (c) a transmitter fortransmitting a third message to said server that indicates whether saidcall is admitted.
 10. The apparatus of claim 9 wherein said firstmessage comprises a SIP acknowledgement message and wherein said secondmessage comprises a SIP invite message.